Design Of Traveling-wave Amplifier Research Articles

Novel Traveling Wave Amplifier Design with Interdigital Grating and 2DEG Substrate for High Gain at 300GHz

We propose a novel traveling wave device operating at sub-THz frequencies. The device structure employs metastuctures for wave slow down to increase gain by 10dB or more. The excitation of the device channel is done using a CPW line with an inserted interdigitated grating. The underlying 2DEG silicon substrate supports an electron beam injected from the drain after source biasing in HEMTs. The proposed device is simulated starting with a 3-D full wave prediction of the field structure to be supported by the interdigital grating within the CPW. This field structure is then used in a 2-D particle-in-cell (PIC) code to predict the device gain. Results from these simulations show more than 10 dB gain at 300 GHz.

A Design of Terahertz Parallel Plate Dielectric Waveguide with Signal Line inserted for Ballistic Deflection Transistor Travelling Wave Amplifier

In this paper a new waveguide design is proposed to be implemented as part of Ballistic Deflection Transistor (BDT) Traveling Wave Amplifier Design. The BDT is designed to be operated in the Terahertz regime. Due to its relatively low transconductance (gm=200µA/V), the entire structure will consist of ten stages, with 15 BDTs/stage, to reach a total gain of 30mA/V. In this case, the total length of the transmission line will be more than 400µm. We did the investigation for different structures and materials of the transmission line. For our Parallel Plate Dielectric Waveguide with Signal Line inserted (PPDWS) design, we are able to get an average loss of 0.46dB/mm at 0.8-1.4THz from ANSYS HFSS simulation. The return loss for input and output are better than -20dB at 0.8-1.7THz. Although it is designed for our future travelling wave amplifier, it can also be used for various other THz frequency applications.

High linearity Josephson-junction array structures

Possible approaches to synthesis of the array structures capable of providing highly linear voltage response have been studied in detail. The first way supposes synthesis of the series array by means of interferometer cells with sinusoidal response. The second one supposes synthesis of differential array structures using interferometer cells with ∣sin(x)∣-like voltage response. The interferometer cells can be replaced by parallel arrays to form a high-performance parallel-series differential structure. The traveling wave amplifier design is suggested to avoid limitations resulting from the distributed nature of the long arrays.

Traveling-wave amplifiers and backward-wave oscillators for VHF

An important aspect of the design of traveling-wave amplifiers and backward-wave oscillators for frequencies below 500 mc is the problem of obtaining a tube of reasonably small physical dimensions. Hollow beams of greater perveance than is obtainable with solid beams offer one method of reducing the size of such tubes by permitting operation at a lower voltage and greater gain per wavelength, for a specified beam power, than is possible in a solid beam tube. Some aspects of the design of minimum size hollow-beam forward-wave amplifiers using single helix circuits and backward-wave oscillators using bifilar helix circuits are presented. Several tubes of these types for operation below 500 mc have been built. Amplifier bandwidths and oscillator tuning ranges in excess of four to one in frequency have been obtained experimentally. Amplifier efficiencies in excess of 20 per cent and oscillator efficiencies in excess of 10 per cent have been achieved.